Vet Watch, May 19

Australia has the dubious honour of being inhabited by a variety of poisonous snakes, including the most venomous snakes in the world. Yay! The Northern Rivers has mainly eastern brown snakes to contend with, as well as the iconic red bellied black snake. Brown snake envenomation is deadly to humans, while black snakes haven’t been associated with human fatalities, but they can make you seriously ill. Our pets unfortunately are frequently killed by both of these species.

Not all bites actually inject venom. Of the 3000 Australians bitten each year by venomous snakes, only about 15% become envenomated and need treatment. Our pets probably have a higher proportion of envenomations since they tend to keep harassing and chewing on snakes even after getting bitten once, and the bite of a brown or black snake is initially not painful and may not even be noticed.

All Australian venomous snakes are Elapids, and all Elapids are associated with paralysis or paresis (partial paralysis) . Paralysis/paresis can also be caused by such things as ticks, puffer fish, snail bait, blood clots, meningitis, cane toads etc. Most of these neurological signs take a while to manifest, whereas most snake envenomation cases progress rapidly, but there is considerable crossover and scope for confusion. Snake envenomation is frequently accompanied by blood clotting disorders as well.

Snake bite symptoms can vary dramatically, but they often follow a course similar to those seen in human patients.

As well as the risk of death due to respiratory/cardiac failure or haemorrhage, some snakes such as black snakes can cause muscle damage that releases toxins (myoglobin) into the blood leading to acute kidney failure. This is sometimes seen as wine-red urine. Black snake bites also can cause local damage and I’ve seen dogs bitten on the back of the tongue that were unable to breathe past the severe swelling.

Treatment can be complex and prolonged due to the myriad ways that snake envenomation can affect the patient. Identifying the species of snake is not always possible.

Brown snake bites can be treated with brown snake anti-venom, but if its not a brown then that’s a complete waste of time. If a black snake is identified, or the species is unknown, then mostly in this district the use of Polyvalent Tiger/Brown Anti-venom is needed. This covers Red Bellied Black Snakes and Rough Scaled Snakes as well.

More than one vial is often required. Brown snake bites sometimes need up to 6 vials in humans to reverse the blood coagulation problems. In pets, this gets expensive at $600 to $1200 a vial!

Anti-venom is only part of the treatment and it won’t reverse all aspects of the venom. Pets need to be on intravenous fluids, and they need treatment and monitoring for blood loss, pneumonia, pain relief, hypothermia, eye ulcers, heart problems, kidney failure, stoke, infection etc etc.

Pets also will sometimes require mechanical ventilation for respiratory failure. If this is the case, it usually needs to be carried out at a specialist facility. Mechanical ventilation is a very intensive procedure, requiring constant monitoring by several trained staff. It can cost $2000 a day and may be required for several days, with no guarantee of success. Depressing but true. About 25% of snake bite cases will die even with the most intense therapy.

So, keep an eye on your pets and don’t let them roam, especially in the early evening when snakes are out looking for mice and other morsels. There’s no effective snake repellents, and home remedies or nutraceuticals such as Vitamin C will do zero to treat a bite. If you think your pet has been bitten by a venomous snake, then keep it quiet and call a vet. Not everyone is equipped to treat snakebite so don’t just turn up unannounced.